<?php
/////////////////////////////////////////////////////////////////
/// getID3() by James Heinrich <info@getid3.org>               //
//  available at http://getid3.sourceforge.net                 //
//            or http://www.getid3.org                         //
//                                                             //
//  FLV module by Seth Kaufman <sethØwhirl-i-gig*com>          //
//                                                             //
//  * version 0.1 (26 June 2005)                               //
//                                                             //
//                                                             //
//  * version 0.1.1 (15 July 2005)                             //
//  minor modifications by James Heinrich <info@getid3.org>    //
//                                                             //
//  * version 0.2 (22 February 2006)                           //
//  Support for On2 VP6 codec and meta information             //
//    by Steve Webster <steve.websterØfeaturecreep*com>        //
//                                                             //
//  * version 0.3 (15 June 2006)                               //
//  Modified to not read entire file into memory               //
//    by James Heinrich <info@getid3.org>                      //
//                                                             //
//  * version 0.4 (07 December 2007)                           //
//  Bugfixes for incorrectly parsed FLV dimensions             //
//    and incorrect parsing of onMetaTag                       //
//    by Evgeny Moysevich <moysevichØgmail*com>                //
//                                                             //
//  * version 0.5 (21 May 2009)                                //
//  Fixed parsing of audio tags and added additional codec     //
//    details. The duration is now read from onMetaTag (if     //
//    exists), rather than parsing whole file                  //
//    by Nigel Barnes <ngbarnesØhotmail*com>                   //
//                                                             //
//  * version 0.6 (24 May 2009)                                //
//  Better parsing of files with h264 video                    //
//    by Evgeny Moysevich <moysevichØgmail*com>                //
//                                                             //
//  * version 0.6.1 (30 May 2011)                              //
//    prevent infinite loops in expGolombUe()                  //
//                                                             //
/////////////////////////////////////////////////////////////////
//                                                             //
// module.audio-video.flv.php                                  //
// module for analyzing Shockwave Flash Video files            //
// dependencies: NONE                                          //
//                                                            ///
/////////////////////////////////////////////////////////////////

define('GETID3_FLV_TAG_AUDIO', 8);
define('GETID3_FLV_TAG_VIDEO', 9);
define('GETID3_FLV_TAG_META', 18);

define('GETID3_FLV_VIDEO_H263', 2);
define('GETID3_FLV_VIDEO_SCREEN', 3);
define('GETID3_FLV_VIDEO_VP6FLV', 4);
define('GETID3_FLV_VIDEO_VP6FLV_ALPHA', 5);
define('GETID3_FLV_VIDEO_SCREENV2', 6);
define('GETID3_FLV_VIDEO_H264', 7);

define('H264_AVC_SEQUENCE_HEADER', 0);
define('H264_PROFILE_BASELINE', 66);
define('H264_PROFILE_MAIN', 77);
define('H264_PROFILE_EXTENDED', 88);
define('H264_PROFILE_HIGH', 100);
define('H264_PROFILE_HIGH10', 110);
define('H264_PROFILE_HIGH422', 122);
define('H264_PROFILE_HIGH444', 144);
define('H264_PROFILE_HIGH444_PREDICTIVE', 244);

class getid3_flv extends getid3_handler
{
    public $max_frames = 100000; // break out of the loop if too many frames have been scanned; only scan this many if meta frame does not contain useful duration

    public function Analyze()
    {
        $info = & $this->getid3->info;

        fseek($this->getid3->fp, $info['avdataoffset'], SEEK_SET);

        $FLVdataLength = $info['avdataend'] - $info['avdataoffset'];
        $FLVheader = fread($this->getid3->fp, 5);

        $info['fileformat'] = 'flv';
        $info['flv']['header']['signature'] = substr($FLVheader, 0, 3);
        $info['flv']['header']['version'] = getid3_lib::BigEndian2Int(substr($FLVheader, 3, 1));
        $TypeFlags = getid3_lib::BigEndian2Int(substr($FLVheader, 4, 1));

        $magic = 'FLV';
        if ($info['flv']['header']['signature'] != $magic) {
            $info['error'][] = 'Expecting "' . getid3_lib::PrintHexBytes($magic) . '" at offset ' . $info['avdataoffset'] . ', found "' . getid3_lib::PrintHexBytes($info['flv']['header']['signature']) . '"';
            unset($info['flv']);
            unset($info['fileformat']);
            return false;
        }

        $info['flv']['header']['hasAudio'] = (bool)($TypeFlags & 0x04);
        $info['flv']['header']['hasVideo'] = (bool)($TypeFlags & 0x01);

        $FrameSizeDataLength = getid3_lib::BigEndian2Int(fread($this->getid3->fp, 4));
        $FLVheaderFrameLength = 9;
        if ($FrameSizeDataLength > $FLVheaderFrameLength) {
            fseek($this->getid3->fp, $FrameSizeDataLength - $FLVheaderFrameLength, SEEK_CUR);
        }
        $Duration = 0;
        $found_video = false;
        $found_audio = false;
        $found_meta = false;
        $found_valid_meta_playtime = false;
        $tagParseCount = 0;
        $info['flv']['framecount'] = array('total' => 0, 'audio' => 0, 'video' => 0);
        $flv_framecount = & $info['flv']['framecount'];
        while (((ftell($this->getid3->fp) + 16) < $info['avdataend']) && (($tagParseCount++ <= $this->max_frames) || !$found_valid_meta_playtime)) {
            $ThisTagHeader = fread($this->getid3->fp, 16);

            $PreviousTagLength = getid3_lib::BigEndian2Int(substr($ThisTagHeader, 0, 4));
            $TagType = getid3_lib::BigEndian2Int(substr($ThisTagHeader, 4, 1));
            $DataLength = getid3_lib::BigEndian2Int(substr($ThisTagHeader, 5, 3));
            $Timestamp = getid3_lib::BigEndian2Int(substr($ThisTagHeader, 8, 3));
            $LastHeaderByte = getid3_lib::BigEndian2Int(substr($ThisTagHeader, 15, 1));
            $NextOffset = ftell($this->getid3->fp) - 1 + $DataLength;
            if ($Timestamp > $Duration) {
                $Duration = $Timestamp;
            }

            $flv_framecount['total']++;
            switch ($TagType) {
                case GETID3_FLV_TAG_AUDIO:
                    $flv_framecount['audio']++;
                    if (!$found_audio) {
                        $found_audio = true;
                        $info['flv']['audio']['audioFormat'] = ($LastHeaderByte >> 4) & 0x0F;
                        $info['flv']['audio']['audioRate'] = ($LastHeaderByte >> 2) & 0x03;
                        $info['flv']['audio']['audioSampleSize'] = ($LastHeaderByte >> 1) & 0x01;
                        $info['flv']['audio']['audioType'] = $LastHeaderByte & 0x01;
                    }
                    break;

                case GETID3_FLV_TAG_VIDEO:
                    $flv_framecount['video']++;
                    if (!$found_video) {
                        $found_video = true;
                        $info['flv']['video']['videoCodec'] = $LastHeaderByte & 0x07;

                        $FLVvideoHeader = fread($this->getid3->fp, 11);

                        if ($info['flv']['video']['videoCodec'] == GETID3_FLV_VIDEO_H264) {
                            // this code block contributed by: moysevichØgmail*com

                            $AVCPacketType = getid3_lib::BigEndian2Int(substr($FLVvideoHeader, 0, 1));
                            if ($AVCPacketType == H264_AVC_SEQUENCE_HEADER) {
                                //	read AVCDecoderConfigurationRecord
                                $configurationVersion = getid3_lib::BigEndian2Int(substr($FLVvideoHeader, 4, 1));
                                $AVCProfileIndication = getid3_lib::BigEndian2Int(substr($FLVvideoHeader, 5, 1));
                                $profile_compatibility = getid3_lib::BigEndian2Int(substr($FLVvideoHeader, 6, 1));
                                $lengthSizeMinusOne = getid3_lib::BigEndian2Int(substr($FLVvideoHeader, 7, 1));
                                $numOfSequenceParameterSets = getid3_lib::BigEndian2Int(substr($FLVvideoHeader, 8, 1));

                                if (($numOfSequenceParameterSets & 0x1F) != 0) {
                                    //	there is at least one SequenceParameterSet
                                    //	read size of the first SequenceParameterSet
                                    //$spsSize = getid3_lib::BigEndian2Int(substr($FLVvideoHeader, 9, 2));
                                    $spsSize = getid3_lib::LittleEndian2Int(substr($FLVvideoHeader, 9, 2));
                                    //	read the first SequenceParameterSet
                                    $sps = fread($this->getid3->fp, $spsSize);
                                    if (strlen($sps) == $spsSize) { //	make sure that whole SequenceParameterSet was red
                                        $spsReader = new AVCSequenceParameterSetReader($sps);
                                        $spsReader->readData();
                                        $info['video']['resolution_x'] = $spsReader->getWidth();
                                        $info['video']['resolution_y'] = $spsReader->getHeight();
                                    }
                                }
                            }
                            // end: moysevichØgmail*com

                        } elseif ($info['flv']['video']['videoCodec'] == GETID3_FLV_VIDEO_H263) {

                            $PictureSizeType = (getid3_lib::BigEndian2Int(substr($FLVvideoHeader, 3, 2))) >> 7;
                            $PictureSizeType = $PictureSizeType & 0x0007;
                            $info['flv']['header']['videoSizeType'] = $PictureSizeType;
                            switch ($PictureSizeType) {
                                case 0:
                                    //$PictureSizeEnc = getid3_lib::BigEndian2Int(substr($FLVvideoHeader, 5, 2));
                                    //$PictureSizeEnc <<= 1;
                                    //$info['video']['resolution_x'] = ($PictureSizeEnc & 0xFF00) >> 8;
                                    //$PictureSizeEnc = getid3_lib::BigEndian2Int(substr($FLVvideoHeader, 6, 2));
                                    //$PictureSizeEnc <<= 1;
                                    //$info['video']['resolution_y'] = ($PictureSizeEnc & 0xFF00) >> 8;

                                    $PictureSizeEnc['x'] = getid3_lib::BigEndian2Int(substr($FLVvideoHeader, 4, 2));
                                    $PictureSizeEnc['y'] = getid3_lib::BigEndian2Int(substr($FLVvideoHeader, 5, 2));
                                    $PictureSizeEnc['x'] >>= 7;
                                    $PictureSizeEnc['y'] >>= 7;
                                    $info['video']['resolution_x'] = $PictureSizeEnc['x'] & 0xFF;
                                    $info['video']['resolution_y'] = $PictureSizeEnc['y'] & 0xFF;
                                    break;

                                case 1:
                                    $PictureSizeEnc['x'] = getid3_lib::BigEndian2Int(substr($FLVvideoHeader, 4, 3));
                                    $PictureSizeEnc['y'] = getid3_lib::BigEndian2Int(substr($FLVvideoHeader, 6, 3));
                                    $PictureSizeEnc['x'] >>= 7;
                                    $PictureSizeEnc['y'] >>= 7;
                                    $info['video']['resolution_x'] = $PictureSizeEnc['x'] & 0xFFFF;
                                    $info['video']['resolution_y'] = $PictureSizeEnc['y'] & 0xFFFF;
                                    break;

                                case 2:
                                    $info['video']['resolution_x'] = 352;
                                    $info['video']['resolution_y'] = 288;
                                    break;

                                case 3:
                                    $info['video']['resolution_x'] = 176;
                                    $info['video']['resolution_y'] = 144;
                                    break;

                                case 4:
                                    $info['video']['resolution_x'] = 128;
                                    $info['video']['resolution_y'] = 96;
                                    break;

                                case 5:
                                    $info['video']['resolution_x'] = 320;
                                    $info['video']['resolution_y'] = 240;
                                    break;

                                case 6:
                                    $info['video']['resolution_x'] = 160;
                                    $info['video']['resolution_y'] = 120;
                                    break;

                                default:
                                    $info['video']['resolution_x'] = 0;
                                    $info['video']['resolution_y'] = 0;
                                    break;

                            }
                        }
                        $info['video']['pixel_aspect_ratio'] = $info['video']['resolution_x'] / $info['video']['resolution_y'];
                    }
                    break;

                // Meta tag
                case GETID3_FLV_TAG_META:
                    if (!$found_meta) {
                        $found_meta = true;
                        fseek($this->getid3->fp, -1, SEEK_CUR);
                        $datachunk = fread($this->getid3->fp, $DataLength);
                        $AMFstream = new AMFStream($datachunk);
                        $reader = new AMFReader($AMFstream);
                        $eventName = $reader->readData();
                        $info['flv']['meta'][$eventName] = $reader->readData();
                        unset($reader);

                        $copykeys = array('framerate' => 'frame_rate', 'width' => 'resolution_x', 'height' => 'resolution_y', 'audiodatarate' => 'bitrate', 'videodatarate' => 'bitrate');
                        foreach ($copykeys as $sourcekey => $destkey) {
                            if (isset($info['flv']['meta']['onMetaData'][$sourcekey])) {
                                switch ($sourcekey) {
                                    case 'width':
                                    case 'height':
                                        $info['video'][$destkey] = intval(round($info['flv']['meta']['onMetaData'][$sourcekey]));
                                        break;
                                    case 'audiodatarate':
                                        $info['audio'][$destkey] = getid3_lib::CastAsInt(round($info['flv']['meta']['onMetaData'][$sourcekey] * 1000));
                                        break;
                                    case 'videodatarate':
                                    case 'frame_rate':
                                    default:
                                        $info['video'][$destkey] = $info['flv']['meta']['onMetaData'][$sourcekey];
                                        break;
                                }
                            }
                        }
                        if (!empty($info['flv']['meta']['onMetaData']['duration'])) {
                            $found_valid_meta_playtime = true;
                        }
                    }
                    break;

                default:
                    // noop
                    break;
            }
            fseek($this->getid3->fp, $NextOffset, SEEK_SET);
        }

        $info['playtime_seconds'] = $Duration / 1000;
        if ($info['playtime_seconds'] > 0) {
            $info['bitrate'] = (($info['avdataend'] - $info['avdataoffset']) * 8) / $info['playtime_seconds'];
        }

        if ($info['flv']['header']['hasAudio']) {
            $info['audio']['codec'] = $this->FLVaudioFormat($info['flv']['audio']['audioFormat']);
            $info['audio']['sample_rate'] = $this->FLVaudioRate($info['flv']['audio']['audioRate']);
            $info['audio']['bits_per_sample'] = $this->FLVaudioBitDepth($info['flv']['audio']['audioSampleSize']);

            $info['audio']['channels'] = $info['flv']['audio']['audioType'] + 1; // 0=mono,1=stereo
            $info['audio']['lossless'] = ($info['flv']['audio']['audioFormat'] ? false : true); // 0=uncompressed
            $info['audio']['dataformat'] = 'flv';
        }
        if (!empty($info['flv']['header']['hasVideo'])) {
            $info['video']['codec'] = $this->FLVvideoCodec($info['flv']['video']['videoCodec']);
            $info['video']['dataformat'] = 'flv';
            $info['video']['lossless'] = false;
        }

        // Set information from meta
        if (!empty($info['flv']['meta']['onMetaData']['duration'])) {
            $info['playtime_seconds'] = $info['flv']['meta']['onMetaData']['duration'];
            $info['bitrate'] = (($info['avdataend'] - $info['avdataoffset']) * 8) / $info['playtime_seconds'];
        }
        if (isset($info['flv']['meta']['onMetaData']['audiocodecid'])) {
            $info['audio']['codec'] = $this->FLVaudioFormat($info['flv']['meta']['onMetaData']['audiocodecid']);
        }
        if (isset($info['flv']['meta']['onMetaData']['videocodecid'])) {
            $info['video']['codec'] = $this->FLVvideoCodec($info['flv']['meta']['onMetaData']['videocodecid']);
        }
        return true;
    }


    public function FLVaudioFormat($id)
    {
        $FLVaudioFormat = array(
            0 => 'Linear PCM, platform endian',
            1 => 'ADPCM',
            2 => 'mp3',
            3 => 'Linear PCM, little endian',
            4 => 'Nellymoser 16kHz mono',
            5 => 'Nellymoser 8kHz mono',
            6 => 'Nellymoser',
            7 => 'G.711A-law logarithmic PCM',
            8 => 'G.711 mu-law logarithmic PCM',
            9 => 'reserved',
            10 => 'AAC',
            11 => false, // unknown?
            12 => false, // unknown?
            13 => false, // unknown?
            14 => 'mp3 8kHz',
            15 => 'Device-specific sound',
        );
        return (isset($FLVaudioFormat[$id]) ? $FLVaudioFormat[$id] : false);
    }

    public function FLVaudioRate($id)
    {
        $FLVaudioRate = array(
            0 => 5500,
            1 => 11025,
            2 => 22050,
            3 => 44100,
        );
        return (isset($FLVaudioRate[$id]) ? $FLVaudioRate[$id] : false);
    }

    public function FLVaudioBitDepth($id)
    {
        $FLVaudioBitDepth = array(
            0 => 8,
            1 => 16,
        );
        return (isset($FLVaudioBitDepth[$id]) ? $FLVaudioBitDepth[$id] : false);
    }

    public function FLVvideoCodec($id)
    {
        $FLVvideoCodec = array(
            GETID3_FLV_VIDEO_H263 => 'Sorenson H.263',
            GETID3_FLV_VIDEO_SCREEN => 'Screen video',
            GETID3_FLV_VIDEO_VP6FLV => 'On2 VP6',
            GETID3_FLV_VIDEO_VP6FLV_ALPHA => 'On2 VP6 with alpha channel',
            GETID3_FLV_VIDEO_SCREENV2 => 'Screen video v2',
            GETID3_FLV_VIDEO_H264 => 'Sorenson H.264',
        );
        return (isset($FLVvideoCodec[$id]) ? $FLVvideoCodec[$id] : false);
    }
}

class AMFStream
{
    public $bytes;
    public $pos;

    public function AMFStream(&$bytes)
    {
        $this->bytes =& $bytes;
        $this->pos = 0;
    }

    public function readByte()
    {
        return getid3_lib::BigEndian2Int(substr($this->bytes, $this->pos++, 1));
    }

    public function readInt()
    {
        return ($this->readByte() << 8) + $this->readByte();
    }

    public function readLong()
    {
        return ($this->readByte() << 24) + ($this->readByte() << 16) + ($this->readByte() << 8) + $this->readByte();
    }

    public function readDouble()
    {
        return getid3_lib::BigEndian2Float($this->read(8));
    }

    public function readUTF()
    {
        $length = $this->readInt();
        return $this->read($length);
    }

    public function readLongUTF()
    {
        $length = $this->readLong();
        return $this->read($length);
    }

    public function read($length)
    {
        $val = substr($this->bytes, $this->pos, $length);
        $this->pos += $length;
        return $val;
    }

    public function peekByte()
    {
        $pos = $this->pos;
        $val = $this->readByte();
        $this->pos = $pos;
        return $val;
    }

    public function peekInt()
    {
        $pos = $this->pos;
        $val = $this->readInt();
        $this->pos = $pos;
        return $val;
    }

    public function peekLong()
    {
        $pos = $this->pos;
        $val = $this->readLong();
        $this->pos = $pos;
        return $val;
    }

    public function peekDouble()
    {
        $pos = $this->pos;
        $val = $this->readDouble();
        $this->pos = $pos;
        return $val;
    }

    public function peekUTF()
    {
        $pos = $this->pos;
        $val = $this->readUTF();
        $this->pos = $pos;
        return $val;
    }

    public function peekLongUTF()
    {
        $pos = $this->pos;
        $val = $this->readLongUTF();
        $this->pos = $pos;
        return $val;
    }
}

class AMFReader
{
    public $stream;

    public function AMFReader(&$stream)
    {
        $this->stream =& $stream;
    }

    public function readData()
    {
        $value = null;

        $type = $this->stream->readByte();
        switch ($type) {

            // Double
            case 0:
                $value = $this->readDouble();
                break;

            // Boolean
            case 1:
                $value = $this->readBoolean();
                break;

            // String
            case 2:
                $value = $this->readString();
                break;

            // Object
            case 3:
                $value = $this->readObject();
                break;

            // null
            case 6:
                return null;
                break;

            // Mixed array
            case 8:
                $value = $this->readMixedArray();
                break;

            // Array
            case 10:
                $value = $this->readArray();
                break;

            // Date
            case 11:
                $value = $this->readDate();
                break;

            // Long string
            case 13:
                $value = $this->readLongString();
                break;

            // XML (handled as string)
            case 15:
                $value = $this->readXML();
                break;

            // Typed object (handled as object)
            case 16:
                $value = $this->readTypedObject();
                break;

            // Long string
            default:
                $value = '(unknown or unsupported data type)';
                break;
        }

        return $value;
    }

    public function readDouble()
    {
        return $this->stream->readDouble();
    }

    public function readBoolean()
    {
        return $this->stream->readByte() == 1;
    }

    public function readString()
    {
        return $this->stream->readUTF();
    }

    public function readObject()
    {
        // Get highest numerical index - ignored
//		$highestIndex = $this->stream->readLong();

        $data = array();

        while ($key = $this->stream->readUTF()) {
            $data[$key] = $this->readData();
        }
        // Mixed array record ends with empty string (0x00 0x00) and 0x09
        if (($key == '') && ($this->stream->peekByte() == 0x09)) {
            // Consume byte
            $this->stream->readByte();
        }
        return $data;
    }

    public function readMixedArray()
    {
        // Get highest numerical index - ignored
        $highestIndex = $this->stream->readLong();

        $data = array();

        while ($key = $this->stream->readUTF()) {
            if (is_numeric($key)) {
                $key = (float)$key;
            }
            $data[$key] = $this->readData();
        }
        // Mixed array record ends with empty string (0x00 0x00) and 0x09
        if (($key == '') && ($this->stream->peekByte() == 0x09)) {
            // Consume byte
            $this->stream->readByte();
        }

        return $data;
    }

    public function readArray()
    {
        $length = $this->stream->readLong();
        $data = array();

        for ($i = 0; $i < $length; $i++) {
            $data[] = $this->readData();
        }
        return $data;
    }

    public function readDate()
    {
        $timestamp = $this->stream->readDouble();
        $timezone = $this->stream->readInt();
        return $timestamp;
    }

    public function readLongString()
    {
        return $this->stream->readLongUTF();
    }

    public function readXML()
    {
        return $this->stream->readLongUTF();
    }

    public function readTypedObject()
    {
        $className = $this->stream->readUTF();
        return $this->readObject();
    }
}

class AVCSequenceParameterSetReader
{
    public $sps;
    public $start = 0;
    public $currentBytes = 0;
    public $currentBits = 0;
    public $width;
    public $height;

    public function AVCSequenceParameterSetReader($sps)
    {
        $this->sps = $sps;
    }

    public function readData()
    {
        $this->skipBits(8);
        $this->skipBits(8);
        $profile = $this->getBits(8); //	read profile
        $this->skipBits(16);
        $this->expGolombUe(); //	read sps id
        if (in_array($profile, array(H264_PROFILE_HIGH, H264_PROFILE_HIGH10, H264_PROFILE_HIGH422, H264_PROFILE_HIGH444, H264_PROFILE_HIGH444_PREDICTIVE))) {
            if ($this->expGolombUe() == 3) {
                $this->skipBits(1);
            }
            $this->expGolombUe();
            $this->expGolombUe();
            $this->skipBits(1);
            if ($this->getBit()) {
                for ($i = 0; $i < 8; $i++) {
                    if ($this->getBit()) {
                        $size = $i < 6 ? 16 : 64;
                        $lastScale = 8;
                        $nextScale = 8;
                        for ($j = 0; $j < $size; $j++) {
                            if ($nextScale != 0) {
                                $deltaScale = $this->expGolombUe();
                                $nextScale = ($lastScale + $deltaScale + 256) % 256;
                            }
                            if ($nextScale != 0) {
                                $lastScale = $nextScale;
                            }
                        }
                    }
                }
            }
        }
        $this->expGolombUe();
        $pocType = $this->expGolombUe();
        if ($pocType == 0) {
            $this->expGolombUe();
        } elseif ($pocType == 1) {
            $this->skipBits(1);
            $this->expGolombSe();
            $this->expGolombSe();
            $pocCycleLength = $this->expGolombUe();
            for ($i = 0; $i < $pocCycleLength; $i++) {
                $this->expGolombSe();
            }
        }
        $this->expGolombUe();
        $this->skipBits(1);
        $this->width = ($this->expGolombUe() + 1) * 16;
        $heightMap = $this->expGolombUe() + 1;
        $this->height = (2 - $this->getBit()) * $heightMap * 16;
    }

    public function skipBits($bits)
    {
        $newBits = $this->currentBits + $bits;
        $this->currentBytes += (int)floor($newBits / 8);
        $this->currentBits = $newBits % 8;
    }

    public function getBit()
    {
        $result = (getid3_lib::BigEndian2Int(substr($this->sps, $this->currentBytes, 1)) >> (7 - $this->currentBits)) & 0x01;
        $this->skipBits(1);
        return $result;
    }

    public function getBits($bits)
    {
        $result = 0;
        for ($i = 0; $i < $bits; $i++) {
            $result = ($result << 1) + $this->getBit();
        }
        return $result;
    }

    public function expGolombUe()
    {
        $significantBits = 0;
        $bit = $this->getBit();
        while ($bit == 0) {
            $significantBits++;
            $bit = $this->getBit();

            if ($significantBits > 31) {
                // something is broken, this is an emergency escape to prevent infinite loops
                return 0;
            }
        }
        return (1 << $significantBits) + $this->getBits($significantBits) - 1;
    }

    public function expGolombSe()
    {
        $result = $this->expGolombUe();
        if (($result & 0x01) == 0) {
            return -($result >> 1);
        } else {
            return ($result + 1) >> 1;
        }
    }

    public function getWidth()
    {
        return $this->width;
    }

    public function getHeight()
    {
        return $this->height;
    }
}
